If you distrust cloud services to prefer playing locally hosted files of music you own, you can use a memory stick, hard drive or NAS via the USB-A host port. That works flawlessly as does Bluebooth 4.2 A2DP reception from wireless mobile kit. There are two S/PDIF inputs for digital source and two analog line inputs. There's Roon Ready to interface with external Roon Core and App. Ditto multi-room or spinning vinyl into the 45kΩ/150pF moving-magnet input. Use the Source II as preamp into a power amp or active speakers. To circumvent the volume control, activate 'fixed line out' in the app, another new feature. Turning D into A are two AKM AK 4493 chips which Lindemann find to offer exceptionally low distortion, natural colors and perfect timing. "These chips work in mono mode so one per channel. All incoming signal undergoes advanced resampling and the MEMS femto clock insures that only jitter-free data presents at the converters." If desired, the app can resample PCM to DSD526 as "the musical 'i' dot". Native PCM only sees synchronous resampling without sample rate alteration. Listening showed DSD resampling to sound just a bit more fine and natural so all my observations were made in DSD mode.

I also had the Power II class D amp in its high-power 2 x 500wpc/4Ω version [the half-power Power 500 sells for €2'690]. Either match the MusicBook's footprint for perfectly integrated stacking. Beware that the amp only features XLR inputs. If desired, the MusicBook can drive two stereo amps to vertically bi-amp. In that mode the bass amp's gain can be adjusted in ten steps. Over the original amp versions, MkII improves by "bypassing the nCore voltage gain stage" with one of Lindemann's own design. "Brilliant JFet gain and extremely clean power feeds of less than 1µV noise step up the input signal without any interference from the class D power module".

With streaming acting stillborn for two days because my router gave up its ghost, I felt nostalgic so reached for my CD storage. Enter a real heavyweight of a headphone, Hedd's €1'700 HeddPhone. That requires real gumption to get out of 1st gear. Did the MusicBook weaken at the knee? Not by an inch. True, I'd dialed in 12dB of extra gain in the app but even without it the Lindemann showed plenty of power for the Hedd. Sonics were transparent, neutral and a virtual shoo-in for the €2'500 Focal Arche DAC/amp which in the final analysis had just a tad more grip and body. That showed the league in which the MusicBook's 6.3mm port played. Sorry, no XLR balanced alternative.

Time to go sonic in my big rig where the equivalent residential combo was a €4'750  NAD M50.2 streamer without DAC; and the DAC section of the €9'780 McIntosh MA8900 AC integrated. .flac files arrived via my Deezer Hifi account. The Lindemann connected with RCA cables so I compared Mac to MusicBook DACs into €14'000/pr Martin Logan Impression 11A speakers. Cage rage open for business. First note to self? Unexcited. That may read uninspired but paid dividends over the mid and long term. Kit which highlights certain bands soon disappoints because the music gets too hooded, bright, artificial or too whatever. Not here. I heard no emphasis or miss so—minor qualification apart which we'll get to—neutrality. Versus the NAD/McIntosh combo, I jotted down "a bit more lit up and transparent" and "not quite as substantial". I also heard how overdriven e-guitars exhibited more bite. Where the American converter treated "Avernal Gate" from the melancholy Doom Metal of the brilliant new Deceiver album by Khemmis a bit rounder and slightly set back, the Source II showed more forward propulsion. The reason was obvious. The McIntosh lives on the darker, warmer more harmonically saturated side of town. The MusicBook also played equal-opportunity employer. Whether fed CD, USB stick or Deezer/Tidal streams, I heard little difference. If we want to split hairs, off the stick perhaps sounded most energetic and taut.